Configuring and Using Automatic Storage
Management
Automatic Storage Management (ASM)
is a database service that allows the efficient management of disk drives with
24 x 7 availability. ASM can provide management for single SMP machines,
or across multiple nodes of a cluster for Oracle Real Application Clusters (RAC)
support.
ASM has the following characteristics:
 |
It automatically does load balancing in parallel
across all available disk drives to prevent hot spots and maximize performance,
even with rapidly changing data usage patterns. |
|
It prevents fragmentation so that there is
never a need to relocate data to reclaim space. |
|
It does automatic online
disk space reorganization for the incremental addition or removal of storage
capacity. |
|
It can maintain redundant copies of data
to provide fault tolerance, or it can be built on top of vendor-supplied,
reliable storage mechanisms. |
|
Data management is done by selecting the
desired reliability and performance characteristics for classes of data
rather than with human interaction on a per file basis. |
ASM solves many of the difficult management problems of Oracle
databases. As the size of a database server increases in terms of disk drives,
and nodes in a cluster, the traditional techniques for management stop working.
They do not scale efficiently. They become too prone to human error, and they
require independent effort on every node of a cluster. Other tasks, such as
manual load balancing, become so complex that it is no longer a viable solution.
These problems are solved if you have expanding storage needs, and you are faced
with storage management problems that are wasting too many cycles of your time.
ASM does not eliminate any existing database functionality.
Existing databases are able to operate as they always have. Existing databases
using file-systems, RAW devices, or based on Oracle Managed Files, can operate
as they always have. New files may be created as ASM files while old ones are
administered in the old way. Databases can have a mixture of ASM files, Oracle
Managed Files, and manually managed files (RAW), all at the same time. Existing
files can also be migrated to ASM.
To see how ASM works, you can view a series of viewlets that
have been created.
Creating an ASM Instance using DBCA
Automatic rebalancing/stripping and migration to ASM
Mirroring a Disk
| 
Bookmark
